Capacitor switching fault protection method and system based on three-phase cooperative control

Abstract

The invention relates to the technical field of reactive compensation of a power system, and discloses a capacitor switching fault protection method and system based on three-phase cooperative control, and the method comprises the following steps: S1, enabling an A-phase switch element, a B-phase switch element and a C-phase switch element in a three-phase circuit to be under the independent control of an intelligent control unit; s2, the intelligent control unit predefines at least two phases in the three phases as main control phases and defines the remaining phase as a standby cooperative phase; s3, when a conventional capacitor switching operation is executed, the intelligent control unit controls the standby cooperative phase to keep a closed state; s4, when the switching instruction is a disconnection instruction, starting a fault identification process; and S5, when it is judged that the fault phase exists, the intelligent control unit immediately executes collaborative protection operation. According to the invention, by setting the main control phase and the standby cooperative phase, at least two phases of circuits can still be cooperatively disconnected when a single switch fails, so that the formation condition of a resonant circuit is thoroughly blocked.

Description

Technical Field

[0001] This invention relates to the field of reactive power compensation technology in power systems, specifically to a capacitor switching fault protection method and system based on three-phase coordinated control. Background Technology

[0002] In modern industrial production and daily life, inductive loads such as electric motors and transformers are widely used. These devices consume both active and reactive power, leading to a decrease in the power factor of the power grid. A low power factor increases energy losses in transmission lines, reduces the utilization efficiency of power generation equipment, and affects the voltage stability of the power grid. Therefore, reactive power compensation through parallel connection of capacitor banks at the power consumption end to improve the power factor is a necessary technical means to ensure the economical, efficient, and stable operation of the power grid.

[0003] To achieve automatic switching of capacitor banks, existing technologies commonly employ a "two-phase control, one-phase direct connection" control scheme. This scheme uses switching elements on two phases (e.g., phase A and phase C) of the three-phase circuit, while the remaining phase (phase B) is directly connected to the power grid without a switching element. During normal operation, the controller only needs to synchronously switch the switching elements of phases A and C to complete the connection and disconnection of the three-phase capacitor bank. This scheme has been widely used in engineering practice due to its small number of switching elements, low hardware cost, and simple control logic.

[0004] However, the structural simplification of the above scheme comes at the cost of sacrificing system fault tolerance, and it has technical flaws. These flaws lie in the fact that when any controlled phase (e.g., phase C) experiences a "failure to open" (i.e., remaining conductive after receiving a disconnect command) due to mechanical sticking or electrical breakdown, since phase B is permanently conductive, the capacitor bank will form a dangerous LC series resonant circuit with the power grid through the faulty phase C and the permanently conductive phase B. Once this circuit is formed, it can easily induce resonant overvoltages and overcurrents several times the rated values ​​in the system, enough to cause catastrophic damage to the capacitors themselves and other equipment in the power grid instantaneously. Existing technical solutions cannot identify such single-point switching faults, nor do they provide any backup mechanism to disconnect the resonant circuit after a fault occurs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a capacitor switching fault protection method and system based on three-phase coordinated control, which solves the inherent safety defects of the "two-phase control, one-phase direct" capacitor switching scheme commonly used in existing technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a capacitor switching fault protection method based on three-phase coordinated control, comprising the following steps: S1. The switching elements of phase A, phase B and phase C in the three-phase circuit are all placed under the independent control of the intelligent control unit; S2. The intelligent control unit predefines at least two of the three phases as master control phases and defines the remaining phase as a backup coordinating phase; S3. When performing a conventional capacitor switching operation, the intelligent control unit controls the standby coordinating phase to remain closed, and performs open or closed operations on the main control phase according to the switching command; S4. When the switching command is a disconnect command, start the fault identification process. The fault identification process includes continuously monitoring the current parameters of each phase in the main control phase after issuing a disconnect command to the main control phase, and determining whether there is a faulty phase in the main control phase that has not been successfully disconnected based on the current parameters. S5. When the faulty phase is determined to exist, the intelligent control unit immediately performs a collaborative protection operation. The collaborative protection operation includes controlling the backup collaborative phase to switch from a closed state to an open state, and controlling the non-faulty phases in the main control phase other than the faulty phase to remain in an open state.

[0007] In a specific embodiment, the step of determining whether there is a faulty phase that has not been successfully disconnected in the main control phase based on the current parameters specifically includes: after the intelligent control unit issues a disconnection command to the main control phase, a preset waiting window is passed, the duration of which is longer than the maximum response time required for the switching element to disconnect normally; after the waiting window ends, the intelligent control unit collects and calculates the effective current value of each phase in the main control phase; the effective current value of each phase in the main control phase is compared with a preset residual current judgment threshold, and it is further confirmed that only one phase in the main control phase has an effective current value greater than the residual current judgment threshold. Only when this condition is met is the phase finally determined to be the faulty phase.

[0008] Preferably, the method further includes adaptive role rotation. During system operation, the intelligent control unit automatically performs role rotation operations based on preset rotation trigger conditions. This operation includes redefining one phase currently defined as the main control phase as a backup coordinating phase, and simultaneously redefining the phase currently defined as the backup coordinating phase as the main control phase.

[0009] In one specific embodiment, among the main control phases, the phases whose effective current value is greater than or less than the preset input current judgment threshold (overcurrent protection value, capacitance decay protection value) are identified; At the same time, it is confirmed that the effective current value of each phase other than the identified phase in the main control phase is not greater than or less than the preset input current judgment threshold (overcurrent protection value, capacitance decay protection value). The identified phase is ultimately determined to be the faulty phase only when the above identification and confirmation conditions are met simultaneously, thereby triggering subsequent collaborative protection operations.

[0010] In a specific embodiment, the rotation triggering condition includes: the intelligent control unit continuously records and updates the cumulative number of actions of each of the A-phase, B-phase and C-phase switching elements; when the average cumulative number of actions of each phase switching element defined as the main control phase exceeds a preset action number balancing threshold, the rotation triggering condition is met, thereby triggering the role rotation operation.

[0011] Preferably, during the routine capacitor switching operation, a health check of the switching elements is also performed simultaneously. This check includes the intelligent control unit simultaneously measuring the response time of the switching element of that phase each time an open or closed operation is performed on any phase of the main control phase, and assessing the health status of the switching element based on the measured response time.

[0012] In one specific embodiment, the response time is measured by recording the moment when the intelligent control unit issues a state switching command to the phase switch element. The system continuously monitors the current parameters of the phase. When the current parameters of the phase stably cross the preset action confirmation threshold, this moment is recorded as the status confirmation moment. Response time of this operation Determined by the following formula: ; In the formula, This refers to the response time for this operation; This is the moment of status confirmation; The instruction timing for the state transition instruction; Indicates separation; Indicates the first phase of the phase This is the second operation.

[0013] In one specific embodiment, assessing the health status of the phase switching element specifically includes: taking the measured response time... Compared with the pre-stored historical average response time that characterizes the normal performance of the phase switching element A comparison is made; when the following conditions are met, the phase switching element is determined to be in a sub-healthy state, and the intelligent control unit generates an early warning message: ; In the formula, This is the preset response time drift tolerance; This refers to the response time for this operation; This is the historical average response time; The lowercase version of the Greek letter Delta is used here to represent a tiny increment or tolerance value.

[0014] Preferably, the historical average response time is dynamically updated. After each new response time is measured, the intelligent control unit uses an exponentially weighted moving average algorithm to calculate the updated historical average response time using the following formula. and replace the value before the update: ; In the formula, The historical average response time before the update; For smoothing coefficients; This refers to the response time for this operation; This represents the historical average response time.

[0015] In one specific embodiment, the switching element is a magnetic latching relay or a solid-state switch composed of thyristors.

[0016] A second aspect of the present invention provides a capacitor switching fault protection system based on three-phase coordinated control, the system comprising: The parameter acquisition module is used to acquire and provide the current parameters of the A-phase, B-phase and C-phase switching elements in real time; The collaborative control and fault diagnosis module is connected to the parameter acquisition module and is used to receive the current parameters, configure the main control phase and the backup collaborative phase according to the preset strategy; when performing a regular capacitor switching operation, it generates a disconnect or close command for the main control phase; after issuing the disconnect command, it starts the fault identification process, determines whether there is a fault phase according to the current parameters, and generates a collaborative protection operation command when a fault phase is determined to exist. The health status and strategy management module is connected to the collaborative control and fault diagnosis module and the parameter acquisition module, respectively, and is used to perform health status diagnosis of switching elements. The health status diagnosis includes measuring and evaluating the response time of the switching elements to determine their health status. An independent switch execution module, connected to the collaborative control and fault diagnosis module, is used to receive and accurately execute disconnect or close commands and collaborative protection operation commands generated by the independent switch execution module, so as to realize independent physical drive of the A-phase, B-phase and C-phase switch elements.

[0017] This invention provides a capacitor switching fault protection method and system based on three-phase coordinated control. It has the following beneficial effects: 1. This invention places all three-phase switching elements under the independent control of an intelligent control unit, and pre-sets a main control phase and a backup cooperating phase. When a fault is detected in the main control phase, the backup cooperating phase and the other normal main control phase can be disconnected in tandem, thereby completely breaking the circuit condition where a single point fault can cause systemic risks. This method solves the technical problem in the prior art where single-phase switch sticking or breakdown caused by B-phase shoot-through can lead to serious accidents such as resonance, improving the operational safety and fault tolerance of the capacitor switching system.

[0018] 2. This invention, by setting an adaptive role rotation step, can dynamically adjust the master and backup roles of each phase switching element based on the cumulative number of operations. This mechanism solves the problem of uneven wear and performance degradation caused by some switching elements operating frequently while others remain idle for long periods in existing technologies. By balancing the electrical and mechanical losses of each switching element, it achieves the technical effect of extending the overall service life of the system and improving long-term operational reliability.

[0019] 3. This invention enables real-time measurement and evaluation of the response time of each switching element by simultaneously performing health checks on switching elements during routine switching operations. This method compares the current response time with the dynamically updated historical average response time, achieving early warning of switching element performance degradation. This elevates the system's protection capabilities from passive protection after a fault occurs to predictive maintenance before a fault occurs, providing managers with opportunities for proactive intervention, thereby enhancing the system's maintainability and intelligence. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a system architecture diagram of the present invention. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Reference Figure 1 , Figure 1 This is a schematic diagram of the overall process of a capacitor switching fault protection method based on three-phase coordinated control according to an embodiment of the present invention. The present invention provides a capacitor switching fault protection method based on three-phase coordinated control, which, within a complete operating cycle, can include a series of processes such as conventional capacitor switching, switching element health diagnosis, adaptive role rotation, fault identification, and coordinated protection.

[0023] The initial step of this method is to configure the system. First, the switching elements of phases A, B, and C in the three-phase circuit are configured to be independently controlled by an intelligent control unit, establishing three independent control and drive links. Subsequently, the intelligent control unit, according to a preset strategy, configures at least two of the three phases as master control phases to perform routine switching tasks, and configures the remaining phase as a backup coordinating phase to perform coordinated protection operations in the event of a fault.

[0024] During routine capacitor switching operations, the intelligent control unit keeps the backup coordinating phase closed and, based on externally or internally generated switching commands, only performs open or closed operations on the main control phase to switch capacitors. During this routine operation, the intelligent control unit also simultaneously executes a switching element health diagnostic process, evaluating the performance status of the switching elements involved in the operation by measuring parameters such as the response time in real time. Furthermore, based on historical operating data such as the cumulative number of operations of each phase's switching elements, the system automatically performs role rotation between the main control phase and the backup coordinating phase when preset conditions are met, in order to balance the losses of each element.

[0025] When the switching command is a disconnect command, the system initiates a fault identification process. In this process, after issuing a disconnect command to the main control phase, the intelligent control unit continuously monitors the current parameters of each phase within the main control phase. By analyzing the current parameters after the preset waiting window ends, it determines whether there are any faulty phases in the main control phase that failed to disconnect due to mechanical adhesion or electrical breakdown.

[0026] Once the faulty phase is determined, the intelligent control unit immediately and unconditionally switches from the normal operating procedure to the collaborative protection procedure. In this procedure, the intelligent control unit performs collaborative protection operations, including: controlling the backup collaborative phase to switch from its original closed state to an open state; and simultaneously controlling or ensuring that the remaining non-faulty phases in the main control phase, excluding the phase identified as faulty, are in or remain in an open state. Through this collaborative operation, even if the faulty phase cannot be disconnected, the system ensures that at least two phases of the capacitor branch are physically disconnected, thereby preventing the formation of abnormal electrical circuits.

[0027] Reference Figure 1The specific implementation of steps S1 and S2 of the method of the present invention is as follows: The intelligent control unit connects to the independent drive circuits that drive the A-phase, B-phase and C-phase switching elements through its internal general input / output ports to establish three independent control links and realize independent control configuration of the three-phase switching elements; after the configuration is completed, the intelligent control unit performs role initialization when the system is powered on for the first time or resets, and configures two of the three phases, such as A-phase and C-phase, as the main control phases according to the preset strategy, and configures the remaining B-phase as the backup cooperating phase, and stores this role allocation state in non-volatile memory.

[0028] To balance the losses of the switching elements in each phase, the intelligent control unit also performs adaptive role rotation during system operation. The intelligent control unit maintains a cumulative action count counter for each of the A, B, and C phase switching elements in its internal memory. After each open or close operation of the main control phase, the cumulative action count for the corresponding phase is incremented and the storage is updated. After each update, the intelligent control unit determines whether the rotation trigger condition is met, which is determined by the following formula: ; In the formula, This is a boolean value that triggers the rotation condition; when it is true, the character rotation is triggered. This is the set of the current main control phases; The number of main control phases; For the sake of separation The cumulative number of times the switching element has been activated; The preset threshold for balancing the number of actions; The summation symbol represents summation for all elements belonging to the set. elements Perform a traversal and summation.

[0029] When the average cumulative number of actions of each phase switching element defined as the main control phase exceeds the action count balancing threshold, the rotation trigger condition is met, thereby triggering the role rotation operation. The role rotation operation includes redefining one of the phases currently defined as the main control phase as the backup coordinating phase, and simultaneously redefining one of the phases currently defined as the backup coordinating phase as the main control phase, for example, cyclically switching in the order from {A,C} as the main control phase to {A,B} as the main control phase to {B,C} as the main control phase.

[0030] Reference Figure 1The specific implementation of step S3 in the method of the present invention is as follows: When performing a conventional capacitor switching operation, the intelligent control unit calculates the current total power factor of the system based on the real-time collected power parameters, and compares the total power factor with a preset target power factor range. If the current total power factor is lower than the lower limit of the range, a closing command is generated and sent to each phase switch element currently configured as the main control phase. If the current total power factor is higher than the upper limit of the range, a disconnection command is generated and sent to each phase switch element of the main control phase. Throughout the entire process of performing the conventional capacitor switching operation, the switch element configured as the backup cooperating phase always remains in a closed state.

[0031] During the execution of the above-mentioned conventional capacitor switching operations, a health diagnosis of the switching elements is also performed simultaneously. This diagnosis is triggered each time an open or closed operation is performed on any phase of the main control phase. The specific diagnosis process is as follows: First, the intelligent control unit synchronously measures the response time of the switching element of that phase during this operation. Then, based on the measured response time, the intelligent control unit evaluates the health status of the switching element of that phase.

[0032] In one specific implementation, the steps for measuring the response time of the phase switching element in this operation include: recording the moment when the intelligent control unit issues the state switching command to the phase switching element. Simultaneously, the current parameters of this phase are continuously monitored. When the current parameters of this phase stably cross a preset action confirmation threshold, this moment is recorded as the status confirmation moment. Response time of this operation Determined by the following formula: ; In the formula, This refers to the response time for this operation; This is the moment of status confirmation; The instruction timing for the state transition instruction; Indicates separation; Indicates the first phase of the phase This is the second operation.

[0033] The assessment of the health status of this phase switching element specifically includes: measuring the response time... Compared with the pre-stored historical average response time that characterizes the normal performance of the phase switching element The comparison is performed; when the measured response time meets the following condition, the phase switch element is determined to be in a sub-healthy state, and the intelligent control unit generates an early warning message: ; In the formula, This is the preset response time drift tolerance; This refers to the response time for this operation; This is the historical average response time; The lowercase version of the Greek letter Delta is used here to represent a tiny increment or tolerance value.

[0034] Preferably, the historical average response time is dynamically updated. After each new response time is measured, the intelligent control unit uses an exponentially weighted moving average algorithm to calculate the updated historical average response time using the following formula. and replace the value before the update: ; In the formula, The historical average response time before the update; For smoothing coefficients; This refers to the response time for this operation; This represents the historical average response time.

[0035] Reference Figure 1 The specific implementation of step S4 in the method of the present invention is as follows: when the switching command is a disconnect command, the intelligent control unit initiates a fault identification process. The fault identification process includes, after the intelligent control unit issues a disconnect command to the main control phase, a preset waiting window is executed, the duration of which is specified in the provided text. It is greater than the maximum response time required for the switching element to normally disconnect, so as to ensure that all normal switching elements have sufficient time to complete their state switching.

[0036] After the waiting window ends, the intelligent control unit immediately acquires and calculates the effective current value of each phase in the main control phase. For any one phase... (in Its instantaneous current value is In one power frequency cycle Within, its effective current value It can be calculated using the following formula: ; In the formula, Indicates phase The effective value of the current, Indicates the power frequency period, Indicates the starting time of integration. Indicates phase At any moment The instantaneous value of the current; Represents the time variable Integrate the points.

[0037] The intelligent control unit then outputs the effective current values ​​of each phase in the main control phase. Each is compared with the preset residual current judgment threshold. A comparison is made. The residual current judgment threshold is... It is used to distinguish between the small residual current after a normal disconnection and the continuous large current caused by a fault.

[0038] The determination logic for whether there is a faulty phase that has not been successfully disconnected in the main control phase based on the current parameters further includes: the intelligent control unit first identifies whether the effective value of the current in the main control phase is greater than or less than the preset residual current judgment threshold. The phases are judged based on overcurrent protection and capacitance decay protection values, and are marked as suspected fault phases. Simultaneously, the intelligent control unit confirms that the effective current values ​​of all phases in the main control phases, except for the identified suspected fault phases, are not greater than or less than the preset residual current judgment threshold. The identified phase is ultimately determined to be the faulty phase only when both the above identification and confirmation conditions are met simultaneously. This decision-making logic ensures that subsequent collaborative protection operations are triggered only when a single-point continuity fault occurs, avoiding misjudgments caused by multi-point faults or measurement errors.

[0039] Reference Figure 1 The specific implementation of step S5 of the method of the present invention is as follows: when the fault identification process in step S4 determines that the fault exists... When this occurs, the intelligent control unit immediately executes a coordinated protection operation. The purpose of this coordinated protection operation is to physically ensure that at least two phases of the capacitor branch are isolated from the power grid by forcibly disconnecting the backup coordinated phase and another non-faulty main control phase if one phase in the main control phase cannot be disconnected normally, thereby effectively cutting off the circuit and preventing electrical accidents such as resonance.

[0040] The collaborative protection operation specifically includes the following steps: The intelligent control unit immediately sends an "emergency disconnect" command to the switching element currently configured as the backup cooperating phase, forcing it to switch from its current closed state to the open state. This operation ensures that even if the faulty phase continues to conduct, the capacitor circuit loses at least one phase of electrical path.

[0041] The intelligent control unit simultaneously sends signals to the main control phase excluding the faulty phase. The non-faulty phase sends a "keep disconnected" command or confirms that it is already disconnected. This step ensures that while the faulty phase remains on, the other normal main control phase is also disconnected, forming a double physical isolation with the backup cooperating phase, thereby completely cutting off the connection between the capacitor and the power grid.

[0042] Through the above-mentioned coordinated protection operation, even if a single switching element fails to disconnect as instructed due to adhesion or breakdown, the system of the present invention can effectively isolate the capacitor through the joint action of the backup coordinated phase and another non-faulty main control phase, thereby achieving rapid and intelligent protection against capacitor switching faults.

[0043] Reference Figure 2 , Figure 2 This is a functional block diagram of a capacitor switching fault protection system based on three-phase coordinated control according to an embodiment of the present invention. The present invention also provides a capacitor switching fault protection system based on three-phase coordinated control, which serves as the physical carrier for executing the aforementioned method, including a parameter acquisition module, a coordinated control and fault diagnosis module, a health status and strategy management module, and an independent switch execution module.

[0044] The parameter acquisition module includes current transformers or Hall effect current sensors coupled to the A-phase, B-phase, and C-phase circuits respectively, as well as signal conditioning circuits and analog-to-digital converters connected to the sensor outputs. The function of the parameter acquisition module is to continuously acquire the instantaneous current values ​​of each of the three phases in real time. After filtering and amplification by the signal conditioning circuit, the analog current is converted into a high-precision digital signal stream by the analog-to-digital converter and provided to the collaborative control and fault diagnosis module, as well as the health status and strategy management module.

[0045] The collaborative control and fault diagnosis module is implemented by a microcontroller or digital signal processor, and runs a preset control and diagnostic program internally. The collaborative control and fault diagnosis module is connected to the data output terminal of the parameter acquisition module to receive real-time three-phase current digital signals. The core functions of the collaborative control and fault diagnosis module include: configuring the roles of the main control phase and the backup collaborative phase according to a preset strategy; generating disconnect or close commands for the main control phase based on electrical parameters such as the power factor during routine capacitor switching operations; after issuing a disconnect command, initiating the fault identification process, i.e., determining the presence of a faulty phase based on the waiting window and residual current judgment threshold as described in step S4 above, and immediately generating a collaborative protection operation command when a faulty phase is determined to exist; and, if a faulty phase is determined to exist, immediately generating a collaborative protection operation command.

[0046] The health status and strategy management module can be integrated with the collaborative control and fault diagnosis module in the same microcontroller, or implemented by a separate logic unit. The health status and strategy management module is connected to both the collaborative control and fault diagnosis module and the parameter acquisition module, and is specifically used to execute health diagnoses of switching elements and adaptive role rotation strategies. In terms of health diagnostics, the health status and strategy management module records the command issuance time and status confirmation time, and performs the response time measurement and evaluation described in step S3 above to determine the health status of the switching elements. In terms of strategy management, the health status and strategy management module maintains a counter for the cumulative number of actions of each phase's switching elements, executes the adaptive role rotation logic described in step S2 above, and transmits the updated role allocation information to the collaborative control and fault diagnosis module.

[0047] The independent switch execution module is connected to the command output terminal of the collaborative control and fault diagnosis module. The independent switch execution module includes three independent drive circuits, corresponding to the switching elements of phases A, B, and C, respectively. Each drive circuit receives digital command signals from the collaborative control and fault diagnosis module and converts them into electrical signals that can directly drive the corresponding switching element (e.g., a magnetic latching relay or solid-state switch) to perform physical actions, such as a voltage pulse of a specific width or a gate trigger current, thereby achieving precise and independent physical drive of the three-phase switching elements. Electrical isolation between modules is achieved through devices such as optocouplers.

Claims

1. A capacitor switching fault protection method based on three-phase coordinated control, characterized in that, Includes the following steps: S1. The switching elements of phase A, phase B and phase C in the three-phase circuit are all placed under the independent control of the intelligent control unit; S2. The intelligent control unit predefines at least two of the three phases as master control phases and defines the remaining phase as a backup coordinating phase; S3. When performing a conventional capacitor switching operation, the intelligent control unit controls the standby coordinating phase to remain closed, and performs open or closed operations on the main control phase according to the switching command; S4. When the switching command is a disconnect command, start the fault identification process. The fault identification process includes continuously monitoring the current parameters of each phase in the main control phase after issuing a disconnect command to the main control phase, and determining whether there is a faulty phase in the main control phase that has not been successfully disconnected based on the current parameters. S5. When the faulty phase is determined to exist, the intelligent control unit immediately performs a collaborative protection operation. The collaborative protection operation includes controlling the backup collaborative phase to switch from a closed state to an open state, and controlling the non-faulty phases in the main control phase other than the faulty phase to remain in an open state.

2. The capacitor switching fault protection method based on three-phase coordinated control according to claim 1, characterized in that, In step S2, the pre-definition of at least two of the three phases as the main control phases specifically includes: During system operation, the intelligent control unit automatically performs role rotation operations based on preset rotation trigger conditions; The role rotation operation includes redefining one of the phases currently defined as the master control phase as the backup coordination phase, and simultaneously redefining the phase currently defined as the backup coordination phase as the master control phase.

3. The capacitor switching fault protection method based on three-phase coordinated control according to claim 2, characterized in that, The preset rotation triggering conditions specifically include: The intelligent control unit continuously records and updates the cumulative number of actions of each of the A-phase, B-phase, and C-phase switching elements; When the average cumulative number of actions of each phase switching element defined as the main control phase exceeds the preset action number balancing threshold, the rotation trigger condition is met, thereby triggering the role rotation operation.

4. The capacitor switching fault protection method based on three-phase coordinated control according to claim 1, characterized in that, In step S4, determining whether there is a faulty phase in the main control phase that has not been successfully disconnected based on the current parameters specifically includes: After the intelligent control unit sends a disconnect command to the main control phase, a preset waiting window is passed, the duration of which is longer than the maximum response time required for the switching element to disconnect normally. After the waiting window ends, the intelligent control unit collects and calculates the effective current value of each phase in the main control phase; The effective current value of each phase in the main control phase is compared with a preset residual current judgment threshold. When the effective current value of one phase in the main control phase is greater than the residual current judgment threshold, the phase is determined to be the faulty phase.

5. The capacitor switching fault protection method based on three-phase coordinated control according to claim 4, characterized in that, The determination logic for identifying a phase as the faulty phase further includes: Among the main control phases, the phases whose effective current value is greater than or less than the preset input current judgment threshold are identified; And at the same time, it is confirmed that the effective value of the current of each phase other than the identified phase in the main control phase is not greater than or less than the preset input current judgment threshold. The identified phase is ultimately determined to be the faulty phase only when the above identification and confirmation conditions are met simultaneously, thereby triggering subsequent collaborative protection operations.

6. The capacitor switching fault protection method based on three-phase coordinated control according to claim 1, characterized in that, In step S3, during the routine capacitor switching operation, a health check of the switching elements is also performed simultaneously. This check includes: Each time an open or closed operation is performed on any phase of the main control phase, the intelligent control unit synchronously measures the response time of the switching element of that phase for this operation; The intelligent control unit assesses the health status of the phase switching element based on the measured response time.

7. The capacitor switching fault protection method based on three-phase coordinated control according to claim 6, characterized in that, The specific steps for measuring the response time of the phase switching element in this operation include: Record the moment when the intelligent control unit sends a state switching command to the phase switch element; Continuously monitor the current parameters of this phase. When the current parameters of this phase stably cross the preset action confirmation threshold, record this moment as the status confirmation moment. The time difference between the instruction time and the status confirmation time is determined as the response time of this operation.

8. The capacitor switching fault protection method based on three-phase coordinated control according to claim 7, characterized in that, The assessment of the health status of the phase switching element specifically includes: The measured response time is compared with the pre-stored historical average response time that characterizes the normal performance of the phase switching element. When the measured response time exceeds the sum of the historical average response time and the preset response time drift tolerance, the phase switch element is determined to be in a sub-healthy state, and the intelligent control unit generates an early warning message.

9. The capacitor switching fault protection method based on three-phase coordinated control according to claim 8, characterized in that, The historical average response time is dynamically updated, and the update method is as follows: After each new response time is measured, the intelligent control unit uses an exponentially weighted moving average algorithm to calculate the updated historical average response time by combining the current measured response time with the historical average response time before the update, and then replaces the previous value.

10. A capacitor switching fault protection system based on three-phase coordinated control, wherein the capacitor switching fault protection method based on three-phase coordinated control according to any one of claims 1-9 is characterized in that, include: The parameter acquisition module is used to acquire and provide the current parameters of the A-phase, B-phase and C-phase switching elements in real time; The collaborative control and fault diagnosis module is connected to the parameter acquisition module and is used to receive the current parameters and configure the main control phase and the backup collaborative phase according to a preset strategy. When performing a routine capacitor switching operation, a disconnect or close command is generated for the main control phase; after the disconnect command is issued, a fault identification process is initiated to determine whether a faulty phase exists based on the current parameters, and when a faulty phase is determined to exist, a collaborative protection operation command is generated. The health status and strategy management module is connected to the collaborative control and fault diagnosis module and the parameter acquisition module, respectively, and is used to perform health status diagnosis of switching elements. The health status diagnosis includes measuring and evaluating the response time of the switching elements to determine their health status. An independent switch execution module, connected to the collaborative control and fault diagnosis module, is used to receive and accurately execute disconnect or close commands and collaborative protection operation commands generated by the independent switch execution module, so as to realize independent physical drive of the A-phase, B-phase and C-phase switch elements.

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